slide 1. © 2012 invensys. all rights reserved. the names, logos, and taglines identifying the...
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Slide 1
© 2012 Invensys. All Rights Reserved. The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of Invensys or its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.
SSE-02Using the Membrane Unit in PRO/IINew Application Brief U-2
Bernie Unger
North American User GroupOctober 14-16
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Membrane Unit (sometimes called Permeation Unit)
Residue
Permeate
Pi, res
Pi, perm
A simple model to simulate components that can migrate selectively across a membrane.
Composed of a bundle of hollow fibers. Flow passes from the high pressure feed/residue side to the low pressure
permeate side of the fiber
Slide 4
Membrane Unit Assumptions
Constant total pressure on both the permeate and feed/residue side
The driving force is partial pressure as calculated by ideal gas law
The permeate side gas is continually swept away from the membrane
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Membrane Unit
)(** ,, surfiresiii PPAreaKR where:
Ri = Flowrate in std. vol/timeKi = Permeation constant in vol/(time-area-pres)Area = Membrane area Pi = Partial pressure of component i
Pi, res
Pi, surf
Pi, perm
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Membrane Unit
Solution technique Integrate on dArea
Solution characteristics Based on partial pressure, not fugacity, therefore solutions do not
change with change in thermo method Limiting case of small area: Flowrate can be calculated from product
partial pressures Because permeate is continually carried away from the membrane,
a membrane unit with 10 area units will have the exact same performance as ten 1 area unit membrane units in series.
Slide 7
Membrane UnitOil Production with CO2 Injection
Oil/Gas Separator
Oil Product
Condensate
Fuel Gas
Membrane CO2 Recovery
Well ProductionCO2 Injection
CO2 Makeup
Slide 8
Membrane Unit Flowsheet
Slide 9
Membrane Unit Flowsheet considerations
The fuel gas is consumed on plant to drive process equipment. The fuel gas is targeted to 900 Btu/scf for proper equipment
operation. The pressure of the permeate side of the membrane units is
adjusted to achieve the heat content. The pressure drop across the residue side is negligible. Two membrane shells are included to allow intermediate
condensate dropout. The temperature equilibrates between the permeate and the
residue. The product streams have a lower temperature because of the Joule-Thomson effect of the pressure drop.
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Membrane Unit Feed Stream
Rate, 1000*scfh 377.5 Temperature, F 100.00 Pressure, psia 350.00 Molecular Weight 41.3642 Vapor Fraction 1.000
Molar Composition 1 - N2 0.0100 2 - H2S 1.5000E-03 3 - CO2 0.8500 4 - C1 0.0955 5 - C2 0.0150 6 - C3 0.0100 7 - IC4 5.0000E-03 8 - NC4 5.0000E-03 9 - IC5 5.0000E-03 10 - NC5 1.0000E-03 11 - NC6 1.0000E-03 12 - NC7 1.0000E-03
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Membrane Unit Feed Stream
Rate, 1000*scfh 377.5 Temperature, F 100.00 Pressure, psia 350.00 Molecular Weight 41.3642 Vapor Fraction 1.000
Molar Composition 1 - N2 0.0100 2 - H2S 1.5000E-03 3 - CO2 0.8500 4 - C1 0.0955 5 - C2 0.0150 6 - C3 0.0100 7 - IC4 5.0000E-03 8 - NC4 5.0000E-03 9 - IC5 5.0000E-03 10 - NC5 1.0000E-03 11 - NC6 1.0000E-03 12 - NC7 1.0000E-03
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Membrane Unit Vendor Supplied Permeability
Component Permeability Permeability at 75 F at 100 Fscfd/ft3/psi scfd/ft3/psi
N2 0.000499 0.00065 H2S 0.008371 0.009869 CO2 0.008366 0.009858 C1 0.000548 0.000713 C2 0.000323 0.000418C3 0.000091 0.000118 IC4 0.000027 0.000035 NC4 0.000037 0.000047 IC5 0.000028 0.000028 NC5 0.000027 0.000036 NC6 0.000021 0.000029 NC7 0.000019 0.000029
)(** ,, surfiresiii PPAreaKR
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Membrane Unit Permeability Fitted to Arrhenious Form
Component Ki,o Ei
N2 0.1885 33958H2S 0.3337 21146CO2 0.3296 21079C1 0.1985 33809C2 0.1037 33118C3 0.0306 33375IC4 0.0066 32125NC4 0.0099 32125IC5 0.00004116 2314.5NC5 0.0081 32590NC6 0.0268 40960NC7 0.2194 53642
Ki = Ki,o exp[-Ei /(RT)]
R = 10.73159, ft3-psia/R-lb-mol
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Membrane Unit Modeling Flowsheet
Slide 15
Membrane Unit Membrane Unit Icon
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Membrane Unit Membrane Input
Slide 17
Membrane Unit Permeation Calculation
Slide 18
Membrane Unit Solution Technique
Calculators are used to set permeation coefficients. It iteratively retrieves temperature from the membrane unit and recalculates the coefficients based on temperature.
A controller is used to adjust the pressure of the permeate to achieve the heat content of the fuel gas.
Slide 19
Membrane Unit Results